ML20215H207
| ML20215H207 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/16/1986 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| TAC-55831, NUDOCS 8610230020 | |
| Download: ML20215H207 (8) | |
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Bart D WUns Vce Presdent October 16, 1986 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation Attn:
Mr. Steven A. Varga Director, PWR-A Project Directorate No. 3 U.S. Nuclear Regulatory Commission Washington DC 20555
Dear Sir:
TROJAN NUCLEAR PLANT 10 CFR 50 Appendix R Exemption Request The contents of this letter were previously discussed with Mr. Terence Chan Previous information provided relative to the fire protection of your staff.
requirements of Section III.G.2 of Appendix R to 10 CFR 50 are supplemented by this letter. provides a supplement to the previous exemption request for Fire Specifically, an additional exemption from the 20-ft separation Area T1.
criteria is requested. An extension of an automatic sprinkler system is planned to protect the exhaust fans for the emergency diesel generator rooms from an exposure fire in the Turbine Building railroad bay. Your prompt review of this issue is requested so that our scheduled completion date of December 1986 can be met.
We would be pleased to discuss any questions or comments you may have regarding this information.
Sincerely, U=J Bart D. Withers Vice President Nuclear Attachments c:
Mr. Lynn Frank, Director State of Oregon Department of Energy Mr. John B. Martin Regional Administrator, Region V U.S. Nuclear Regulatory Commission lt / I 8610230020 861016 PDR ADOCK 05000344 I
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s Trajan Nucitar Plcnt Mr. Stsvan A. Vargt Docket 50-344 October 16, 1986 o
License NPF-1 Page 1 of 7 SUPPLEMENTAL EXEMPTION REQUEST FOR FIRE AREA Tl An exemption from 10 CFR 50, Appendix R, Section III.G.2.b is requested because four fire dampers located in the 3-hour fire resistive wall between the EDG rooms (Fire Areas T5 and T6) and Turbine Building railroad bay (Fire Area Tl) are not physically separated by 20 feet, as required by Federal Regulations. The concern is that a fire in the railroad bay could cause the fire dampers to close, such that the room exhaust systems for each EDG room would be impaired.
An extension of the wet pipe sprinkler system protecting the EDG ventilation intakes will be installed in the railroad bay to control and extinguish an exposure fire near the north wall of the EDG rooms.
On the following pages, a revised Fire Area T1 exemption request is provided. We anticipate amending Section 5.2.3 of the 10 CFR 50 Appendix R Review, as reflected therein, with the Trojan FSAR update scheduled for July 1, 1987.
4 Trojtn Nucisar Plcnt Mr. Stsvan A. Vargs s
Dockst 50-344 October 16, 1986 License NPF-1 Page 2 of 7 5.2.3 FIRE AREA Tl The 45-ft elevation of,the Turbine Building does not comply with the specific provisions of Section III.G.2 of Appendix R in that there is not 20 ft of horizontal separation free of intervening combustibles between normal and alternate air intakes, and normal air exhausts, for redundant emergency diesel generators (EDGs), or between the air intakes and Train A safe shutdown cables.
Per the provisions of 10 CFR 50.12 PGE requests an exemption from the specific requirement of Section III.G.2 of Appendix R for Fire Area T1 to the extent that redundant trains of safe shutdown equipment and cables be i
separated by a horizontal distance greater than 20 ft with no intervening combustibles or fire hazards, or that one redundant train of equipment or cables be enclosed in a fire barrier having a 1-hr rating.
This exemption request also incorporates an evaluation to confirm the adequacy of partial automatic suppression and detection systems currently installed in this area.
This evaluation is included for the purpose of l
(a) demonstrating compliance with the provisions-of Sections III.G.2.b l
and III.G.2.c of Appendix R, based on the interpretation in Enclosure 1 to Generic Letter 86-10, and (b) obtaining NRC review and concurrence of this evaluation.
Area Description Fire Area T1 includes the general area of the Turbine Building at the 45-ft, 69-ft, and 93-ft elevations. This area is depicted in Figures 2-1 through 2-5.
Area T1 is separated from other fire areas containing redundant safe shutdown equipment by fire barriers, as described in Sec-tion 2.3.7.1.
The fire barriers between areas in the vicinity of the EDG l
j rooms (Areas T1, T5, T6, T8, and C1) are all 3-hr fire rated. The area of interest is depicted in Figure 2-23.
The area is well ventilated and i
allows for air exchange throughout the building.
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Trojan Nuclear Plant Mr. Stsvin A. Virgs Dockst 50-344 Octcbar 16, 1986 License NPF-1 Page 3 of 7 The total floor area for the 45-ft elevation of Area T1 is 30,000 ft.
.There are variable ceiling heights, but.in the vicinity of the EDG air intakes there is 23 ft to the bottom of the partial slab at the 69-ft l
elevation. The combustible loading on Elevation 45 ft comes from a number of sources, but amounts to 23,900 Btu /ft.
There are few fixed combustibles in the Elevation 45-ft corridor near the normal EDG ventila-tion exhausts,- but transient combustibles are possible. Along the south side of the EDG rooms the fixed combustibles consist of cables, lubricant for air compressors, and some hydrogen. These are between the normal intakes on the east side of the Train B EDG room and the alternate intake for Train A EDG on the south side of the Train A EDG room.
There are also combustibles directly above the hallway on the 69-ft level. The combustibles are the Train A cables form the Turbine Building electrical switchgear room (Area C8) and contribute to an average combustible load-ing of 79,600 Btu /ft on the 69-ft elevation, j
Safe Shutdown Equipment Cables for virtually all Train A safe shutdown equipment are routed from the Train A electrical switchgear room to the Control Building above the 69-ft elevation partial slab in the corridor directly above the corridor containing the normal EDG ventilation intakes. Train B safe shutdown cables are routed independently of Area T1 so as to ensure a safe i
shutdown path.
The normal air intakes for both the Train A and B EDCs (VC-161 and VC-162, respectively) are adjacent to one another in the corridor along the east side of the Train B EDG room on the 45-ft elevation. An '
alternate intake for the Train A EDG is on the south side of the Train A EDG room. A detailed description of the ventilation system for the EDG rooms is provided in Section 3.5.2.2.9.
This alternate intake is provided with an automatically actuated motor-operated damper (MO-10405) which is to function in the event of a fire in the Train B EDG room.
The air intake duct for.VC-161 passes through the Train B EDG room. The air intake for l
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Trojen Nuclesr Plant Mr. Stevan A. Vargt Dockst 50-344 October 16, 1986 License NPF-1
-Page 4 of 7 VC-161 is separated from MO-10405 by over 80 ft, around the perimeter of the EDG rooms.
The normal room exhausts for both the Train A and B EDGs are cdjacent to one another in the Turbine Building bay along the north side of the EDG rooms on the 45-ft elevation. Redundant room exhausts are separated by a minimum horizontal distance of 13 ft and are 16 ft above the floor.
Other deviations from Section III.G.2 criteria exist in another portion of Area T1 near the AFW pump rooms. These involve redundant AFW pumps and controls, ventilation for the diesel-driven AFW pump, and DF0 trans-fer pump control cables.
The resolution of these deviations is described in detall in Section 3.8.32.
As these deviations will be resolved in accordance with Section III.G.2 criteria, they are not considered a part of the exemption request and are only mentioned for the sake of complete-ness.
The AFW pump rooms are approximately 100 ft away from the EDG air intakes.
Fire Protection Capabilities There are a significant number of localized fire detection and automatic fire suppression systems throughout Area T1.
These are normally centered in the vicinity of localized fire hazards (eg, feedwater pump lube oil reservoir).
In the corridor containing the ventilation intakes there is an existing automatic sprinkler system providing partial coverage on both sides of a nonrated combination rollup and swinging door. A concrete partition is also provided above this doorway and extends approximately 10 ft down from the Elevation 69-ft floor slab.
The automatic sprinkler system is supplemented by three 20-lb chemical fire extinguishers in or near the corridor, a 150-lb wheeled dry chemical fire extinguisher, and a manual hose station on the south side of the EDG rooms.
Partial area fire suppression coverage is also supplied along the south side of the EDG rooms in the vicinity of the hydrogen seal oil cooler.
This coverage consists of an automatic sprinkler system and runs for
Trojan Nuclear Pla'nt Mr. Stevan A. Varga Docket 50-344 October 16, 1986 License NPF-1 Page 5 of 7 approximately 35 ft along the south wall. This sprinkler system is supplemented by two 20-lb chemical fire extinguishers and a manual hose station.
The Turbine Building bay on the 45-ft elevation is provided with two 20-lb
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dry chemical fire extinguishers and a hose station.
Fire Hazards Analysis Four situations need to be protected against:
(1) A fire in the east corridor contcining the normal EDG ventila-tion intakes spreading to threaten the Train A cables on the 69-ft elevation and/or the alternate intake for the Train A EDG.
(2) A fire along the south side of the EDG room spreading to threaten the alternate intake for the Train A EDG and the normal intakes for both EDCs.
(3) A fire on the 69-ft elevation affecting the Train A cables and the normal intake for the Train B EDG.
(4) A fire in the north Turbine Building railroad bay affecting the room exhausts for both EDGs.
To prevent redundant trains of safe shutdown systems from being impacted, an automatic sprinkler system (providing 3,200 ft coverage) will be installed under the Elevation 69-ft floor slab to prevent propagation of a fire that could affect the redundant EDG air intakes. The ceiling of the corridor (ie, the Elevation 69-ft floor slab) will also be upgraded to a 3-hr-rated firt tarrier. The cencrete partition above the corridor doorway at Elevation 45 ft forms an effective draft stop to assist the sprinkler system in limiting the migration of hot gases and smoke.
Trojan Nuclcar Pla'nt Mr. Stavan A. Vargt Docket 50-344 October 16, 1986 License NPF-1 Page 6 of 7 The features above and the existing sprinkler system along the south side of the EDG rooms will prevent damage to redundant safe shutdown equipment and cables along the most likely directions of fire propagation. The new sprinkler system will not inhibit the function of the normal ventilation intakes.
The normal EDG r'oom exhausts require additional protection beyond the horizontal separation already existing between redundant exhaust ducts.
In the unlikely event that the fire damper in each of the four exhaust ducts were to close from an unmitigated fire in the Turbine Building railroad bay area, the alternate air intake in the south side of the Train A EDG room could not provide adequate room exhaust. Thus, an extension of'the automatic sprinkler system protecting the EDG intakes (providing an additional 2150 ft coverage) ?ill be installed to cover the floor area of the railroad bay at Elcsation 45 ft.
The arca of coverage is between Columns U-S and 41-45 in the Turbine Building.
Furthermore, if the exhaust fans are operating, there will be little or no heat or smoke filtration into the EDG room, r
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Conclusion Based on the analysis above, PGE requests an exemption from the specific requirements of Section III.G.2 of Appendix R for Fire Area Tl to the extent that redundant trains of safe shutdown' equipment and cables be separated by a horizontal distance of greater than 20 ft with no inter-vening combustibles of fire hazards, or that one redundant train of equipment or cables be enclosed in a fire barrier having a 1-hr rating.
The technical bases justifying this exemption are summarized as follows:
l (1) The ceiling of the 45-ft elevation corridor will be l
upgraded to a 3-hr-rated fire Larrier.
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Trajen Nuclear PIEnt Mr. Stevin A. Virgt Dockst 50-344 Octobsr 16, 1986 License NPF-1 Page 7 of.7 (2) Fire detection and/or automatic fire suppression are or will be provided to protect against the hazards in the area.
(3) Manual fire suppression capability is provided throughout the area.
Further modifications required to meet Section III.G of Appendix R, in addition to those described above, would not enhance fire protection above that-proposed.
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